Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of turbine blades. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as for airplanes, including helicopters. In aircraft, gas turbine engines are used for propulsion of the aircraft. In terrestrial applications, turbine engines are often used for power generation.
Gas turbine engines fir aircraft are designed to operate at high temperatures to maximize engine thrust, so cooling of certain engine components, such as the high pressure turbine and the low pressure turbine, may be necessary. Typically, cooling is accomplished by ducting cooler air from the high and/or low pressure compressors to the engine components which require cooling. Temperatures in the high pressure turbine are around 1000° C. to 2000° C. and the cooling fluid from the compressor is about 500 to 700° C. While the compressor air is a high temperature, it is cooler relative to the turbine air, and may be used to cool the turbine. When cooling the turbines, cooling fluid may be supplied to various turbine components, including the interior of the turbine blades and the turbine shroud.
Engine components have been cooled using different methods, including conventional convection cooling and impingement cooling. In conventional convection cooling, cooling fluid flows along a cooling path through the component, and heat is transferred into the flowing air. In impingement cooling, a cooling surface, typically an inner surface, of the component is impinged with high velocity air in order to transfer more heat by convection than with typical convection cooling.
Particles, such as dirt, dust, sand, and other environmental contaminants, in the cooling fluid can cause a loss of cooling and reduced operational time or “time-on-wing” for the aircraft environment. This problem is exacerbated in certain operating environments around the globe where turbine engines are exposed to significant amounts of airborne particles. In the most severe cases the entire cooling surface of the shroud becomes coated with particles, with the additional negative impact of film hole blockage.